Simple Chlorination

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Simple Chlorination

Simple chlorination is the process of adding a small volume of chlorine solution into the top of thewater well, followed by circulating the chlorine into the water supplys distribution system. Thissimplified procedure is used to disinfect the upper portion of a well casing, the well pump, the droppipe, the water service line, the pressure tank, and the building distribution system. As the pump isoperated, the chlorine is drawn to the pump intake and from there into the distribution system.Simple chlorination can be effective for existing water supplies and should not be used for newlyconstructed wells unless sampling shows the well is not the source of the bacterial contamination.

With simple disinfection, there is no assurance that the chlorine will get to the bottom of the well orinto the aquifer around the well. Water is flowing from the bottom of the well up to the pump intake,minimizing the chance that any portion of the well below the pump intake will be exposed to thechlorine. When used for treating existing water supply systems, it should be used only for the firsttreatment. If simple chlorination is unsuccessful at disinfecting the existing well, the bulkdisplacement method of well chlorination (See next section of this manual) should be used.

Disinfection of flowing wells, wells with deep well jet pumps, wells with drawdown seals, or wells inpits should not be attempted by well owners. A registered water well drilling contractor should becontacted to perform well treatment on these types of wells.

Simple Chlorination ProceduresThe following simple chlorination procedures are recommended for treating a typical 4- to 6-inchdiameter home water well system with a submersible pump.

1. Remove Turbidity -If the well water is not clear, pump it to waste until it clears up beforestarting the chlorine treatment. Turbidity (cloudiness) in the water can reduce the effectivenessof the chlorine.

2. Bypass Cartridge Filters - If the water system has a cartridge filter, place its valve in the

bypass position and remove the cartridge housing and cartridge. Discard the old cartridge.Rinse the housing with a solution of 1 tablespoon of bleach and a cup of water. Drain thehousing and insert a new filter cartridge. Reinstall the cartridge housing and filter, but leavethe cartridge filter valve in the bypass position until the chlorine has been completely flushed

from the water supply after treatment.3. Bypass Other Water Treatment Units -Bypass water treatment units, such as water

softeners, reverse osmosis (RO) systems, and iron removal systems. Follow manufacturersrecommendations pertaining to disinfection of treatment units. Then leave the units in by-passposition until all chlorine has been flushed. High concentrations of chlorine can damagesoftener resin (Keller, 1991) and RO membranes.

4. Check Water Well Record -Check the water well record to see if there are drawdown seals orother devices that will prevent chlorine from reaching the water. If there are, or if you areunsure, contact a Michigan registered water well drilling contractor to perform the disinfection.

5. Turn Off Power to the Pump Before Removing the Well Cap.6. Prepare a Chlorine Solution. Prepare a chlorine solution using the table below. Any brand

of unscentedliquid household bleach that contains 5 to 6 percent available sodium

hypochlorite may be used. Swimming pool chlorine and scented products should beavoided.

Chlorine Solution Table

Well Diameter Amount of bleach per 25 feet of well depth

4 inch 1 cup5 inch 1 cups6 inch 2 cups

Example: A 4-inch diameter well 150 feet deep would need 6 cups of bleach to treat the well.


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7. Mix. Mix the bleach (from above chart) with 5 gallons of clean water in a clean plastic orglass container and add an additional 2 cups of bleach (to assure sufficient chlorine fordisinfection of the pressure tank, water heater, and distribution system).

Example: From the chart above, a 4-inch diameter well 150 feet deep would need

6 cups of bleach to treat the well. Therefore, a total of 8 cups of bleach will be mixedwith the 5 gallons of water.

8. Pour. Slowly pour the mixture into the top of the well.9. Circulate.After the chlorine has been applied to the well, turn the pump on and circulate the

chlorinated water through the service lines and plumbing. Attach a hose to an outside tap andrun the water to waste (discharge onto the ground surface) until a chlorine smell can bedetected in the water and the water is clear. Do not discharge the water into a sewagedisposal system.

10. Recirculate. Do not start this process until the water from the hose is clear. Use thegarden hose to recirculate the chlorinated water back into the top of the well. Wash down theinside of the casing for at least 30 minutes. During this process, water circulates from thepump, through the drop pipe, service line, pressure tank, distribution piping, and hose back intothe top of the well. This recirculation of the chlorinated water will help assure a uniformdistribution of chlorine between the top of the water column in the well and the pump intake(Jones, 1979). The recirculation of chlorinated water enhances the chlorination process by not

only exposing surfaces to chlorinated water, but also to the cleaning effect of agitated (flowing)water.

11. Reinstall the Well Cap. After the recirculation period, turn off the water to the hose and cap

the well.12. Open Taps. Open each tap within the home, one at a time, starting closest to the pressure

tank, and run water until a strong chlorine smell is present. Close the tap. Do not forget toflush each hot water tap. See the Distribution System Disinfection section of this manual fora more detailed description of procedures to be used to disinfect a distribution system.

13. Contact Period. Allow the chlorine to remain in the water supply for 4 to 12 hours, preferably

overnight (Lehr, et al., 1988). Contact time is an important part of the chlorine treatmentprocess. The longer the chlorine is allowed to remain in the water supply system, the betterthe chance that the chlorine will contact and kill microorganisms that may be present. Water

use during the contact time should be minimized to assure that a chlorine residual remains inthe well.

14. Flush. After the contact period, pump to waste to remove the chlorine from the water supply.

Flush until the chlorine smell can no longer be detected. After the chlorine smell can no longerbe detected, it is recommended that flushing be continued for an additional 1 to 2 hours, sincethere may still be traces of chlorine in the well. This will help assure that all traces of chlorinehave been removed. Flushing for an extended period of time after treatment with chlorine willalso help clean the system because of the scouring action of the water.

For this period of pumping to waste, use a hose connected to an outside tap, discharging intothe yard, a roadside ditch, etc. If possible, avoid pumping chlorinated water on lawns andlandscape plants. The outside tap should be allowed to run in the fully open position to

maximize the pumping rate.

Do not run the water into the household plumbing, and subsequently into the septictank/tile field, during this pumping period. Overload of the drainfield can occur.

Do not run the water into a lake, stream, or other body of water.

15. Reactivate Treatment Systems. When all traces of chlorine are gone, place the disinfectedwater treatment units back online.


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16. Sample. Collect a bacteriological water sample. Before sampling, a check for residual

chlorine should be done using a chlorine (swimming pool) test kit or a chlorine meter. The useof chlorine test strips is not practical since most strips do not measure concentrations less than1.0 ppm. If a test kit or chlorine meter is not available, continue to flush for at least 2 hoursafter there is no chlorine smell, before collecting the water sample.

Turbidity as a Result of the Chlorination Process

Water from a water supply system that has been treated with chlorine can be turbid due to the effectof the chlorine on minerals in the water (such as iron) and biofilms that may be present. Extendedpumping normally clears the water of turbidity.


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Agitation of a bulk tank using a paddle

Bulk Displacement Chlorination

Bulk displacement is the recommended method of introducing a prepared chlorine solution into awell. It involves preparing a predetermined volume of disinfectant solution and pouring or pumpingthe solution into the well. The chlorine solution displaces water in the casing, screen/borehole, andaquifer, replacing it with the chlorinated solution. This is the most practical method to assure thatchlorine is uniformly distributed throughout the well and reaches the aquifer surrounding the wellintake.

CHLORINE SOLUTION PREPARATION

1. Determine the volume of the chlorine solution that needs to be prepared.The volume of the chlorine solution should be a minimum of 5 times the combined volume ofthe casing and screen/borehole. This volume helps ensure that there is enough disinfectant tofill the casing/borehole and flow out into the aquifer around the screen or rock borehole.

Example - a 125-foot deep well with 5-inch diameter casing, with a static water level of 25 feet

below ground, has a volume of 100 gallons. Therefore, the volume of the stock solutionshould be 500 gallons.

For fractured limestone and other highly porous formations, the volume of the chlorine solutionshould be increased to assure chlorine contact with all contaminants that may have beenintroduced into the formation.

For use in determining casing and screen/borehole volumes, use the following:

2-inch well = .16 gallons per foot4-inch well = .65 gallons per foot5-inch well = 1.0 gallons per foot6-inch well = 1.5 gallons per foot

2. Adjust the pH of the water in the bulk tank to 4.5 before adding chlorine (Optional, butrecommended)Controlling the pH of a chlorine solution is recommended(Coombs, 2001; Mansuy, 2001; Schnieders, June 2001;Smith, 2001), especially when previous disinfectionattempts have been unsuccessful. See the discussion ofpH control in the Factors Affecting Effectiveness ofChlorination section of this manual.

Use a well cleaning acid(carefully followingmanufacturers

instructions) tolower the pH of thechlorine solutionbeing prepared inthe bulk tank to4 to 4.5. After theacid is added tothe water in the

bulk tank, the water must be agitated to assure uniform distribution of the acid. An air line, arecirculating pump, paddles, or other agitation methods should be used.

White distilled vinegar and

chlorine bleach

Adding vinegar to bulk tank


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Use pH test strips to check the pH level. Make sure the pH has stabilized by testing severaltimes.

Caution! At a pH of 5 or below, some chlorine gas is formed. More gas evolves if the pH

drops below 4. Fortunately the chemical reaction forming the chlorine gas is slow at or near apH of 4 and the hypochlorite solution quickly begins to neutralize the acid as soon as it isadded, raising the pH to a safer level. Above a pH of 5, no chlorine gas is produced(Schnieders, February, 1998). Add the acid to the source water only in a well ventilated area,and avoid exposure to the fumes from the acid container.

Do not use source water that has hydrogen sulfide (H2S) present unless the water has beenaerated enough for the H2S to dissipate. Adding an acid to water containing H2S will cause theH2S gas to be immediately released from the water. Exposure to elevated levels of H2S is aserious health risk.

Use Only NSF Certified AcidsThere are several commercial well cleaning products on the market that have been developedto lower the pH of the source water. Many of these products now meet ANSI/NSF StandardNumber 60. Contact a water well supply house or manufacturers website for informationconcerning these products.

Recommended AcidsAcetic Acid:

This is a good biocide and biofilm dispersing acid. Acetic acid is usually sold as glacial aceticacid, which is at least 95 percent (except for vinegar). In this form, it is extremely dangerous andvery corrosive to skin and lungs (Mansuy, 2001; Schnieders, June 2001; Smith, 2001).

Vinegar is a weak form of acetic acid, and can successfully lower the pH of source water(Schnieders, 2001). There are several types of vinegar available in a grocery store, but thewhite distilled vinegaris the recommended type. Vinegar is:

Safe to use. Readily available in most grocery stores.

Inexpensive.

As a General Rule When Using Vinegar-Sources of water to be used for the chlorine

solution may differ in quality and adding the same amount of a specific acid may produceslightly different results from case to case. A general rule is to add 1 gallon of vinegar to each100 gallons of water to lower the pH to the desired starting point of 4 to 4.5 pH (remember toalways check with suitable pH test strips for that range).

Sulfamic Acid:Relatively effective against carbonate scales, but is not effective against biofouling.

Relatively safe to handle.

May form insoluble solids in a water well (Smith, 2001). It produces the sulfamate ion which isvery soluble for up to 6 to 12 hours. After that, it hydrolyzes to sulfate and then produces theinsolubles

Hydroxyacetic Acid:

Good biocidal properties.


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Acids Not RecommendedOxalic Acid:

Fairly dangerous to skin and eyes and produces oxalates, which are poisonous.

Citric Acid:

Food source for bacteria and is difficult to get out of a well.

Muriatic (Hydrochloric) Acid:

Low concentration (20 percent) of hydrochloric acid

Hazardous to handle. Contractors should avoid usingmuriatic acid due to its hazardous properties. Severaldeaths and injuries have occurred in Michigan that wereassociated with use of muriatic acid for water wellrehabilitation (Keech, November 1983)(MichiganDepartment of State Police, 2001)(Oceana CountySheriffs Department, 2001).

Relatively ineffective against biofouling.

Phosphoric Acid:One of the milder mineral acids - Leaves phosphate

residue behind which can stimulate bacterial growth andmagnify biofouling problems. Use of this acid must befollowed by aggressive agitation of the aquifer to removeany of the phosphate residue that may have been deposited.

3. Add chlorine to the source waterAdd chlorine to the source water and agitate to assureproper chlorine distribution. An air line, a recirculatingpump, paddles, or other means of agitation should beused.

Add enough chlorine to obtain a concentration of

approximately 200 ppm chlorine (Schnieders, 2001).

If calcium hypochlorite isused as the source ofchlorine, it should bedissolved in a pail of water before being added to the preparedsource water. After being added to the bulk tank and thoroughlymixed, the calcium carbonate impurities should be allowed tosettle to the bottom of the tank. The clear solution above thesediment is then drawn off for discharge into the water well. Usesodium hypochlorite if the well water has more than 100 ppmdissolved calcium (calcium carbonate).

The addition of chlorine to the source water should take place ina well ventilated area. Hypochlorite fumes or chlorine gas can become concentrated in aconfined area and may cause severe respiratoryproblems.

4. Verify final pH and chlorine concentration

For maximum bactericidal efficiency, the final pH of thechlorine solution should be between 6 and 7.

Avoid the use of muriatic acid

Add chlorine to the bulk tank

to lower the pH

Use a paddle to agitate

pH test kit


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Use a chlorine test kit or meter to verify proper levels ofchlorine and a pH test kit to verify proper levels of pH. Adjustas necessary. Note that the use of pH test strips may not bepractical after the chlorine has been added to the stocksolution because of the bleaching effect of the chlorine on thestrips.

CHLORINE SOLUTION APPLICATION

Use the following procedures to apply the chlorine solution to the well:

1. Pump to waste -Turbidity in the water can reduce the effectiveness of the chlorine. If the wellwater is not clear, pump it to waste until it clears up before starting the chlorine treatment.

2. Bypass treatment units - Bypass water treatment units, such as cartridge filters, watersofteners, reverse osmosis (RO) systems, and iron removal systems. Followingmanufacturers recommendations, disinfect the treatment units with chlorine. Then, leave theunits in by-pass until the chlorine has been completely flushed (high concentrations of chlorinecan damage softener resin and RO membranes, so pay attention to manufacturersinstructions).

3. Application of chlorine solution into the well using bulk displacement -After the chlorine

solution has been prepared (see previous section), apply the chlorine solution into the well.Delivering the chlorine solution with sufficient hydraulic energy to effectively penetrate all areasof the well is crucial (Mansuy, 2001).

Discharging a chlorine solution into a screened well

Assure that the wellhead area is well ventilated, especially if the well is in a confined spacesuch as a well house, well pit, or basement offset. Use appropriate safety precautions andfollow state laws when working in confined spaces.

For screened wells - the chlorine solution may be discharged directly into the top of the well.

The solution will displace the water in the casing and screen, and force the chlorine solutionout into the formation.

For screened wells in extremely coarse formations or where screen lengths over 10 feetare used - a jetting tool extending into the screen to apply the chlorine solution is

recommended. The jetting tool will force the solution further out into the formation, and thejetting action will help break loose cuttings and drilling fluids that have been trapped in thegeologic materials outside the well.

pH test strips


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Examples of typical jetting tools

For rock wells Pump the chlorine solution through a tremie pipe extending to the bottom ofthe borehole and slowly withdraw the tremie pipe as the solution is added. This helpsuniformly distribute the chlorine solution throughout the uncased portion of the borehole. Ajetting tool or other means of agitation is recommended during or after application of thechlorine.

4. Agitation -Agitation of the well is recommended when disinfecting existing wells where

biofilms are likely, or where repeated chlorinations have not been successful. Agitation of thechlorine in the well will help distribute the chlorine into the aquifer, and will enhance thepenetration of the chlorine into slimes, scale, or other bacteria containing material. Therecommended method of agitation is by surge block or jetting tools.

5. Circulation -After the chlorine has been applied to the well, turn the pump on and circulatethe chlorinated water through the service lines and plumbing. Use a garden hose attached toan outside tap to run the water to waste (discharge onto the ground surface) until a chlorinesmell can be detected in the water and the water is clear.

6. Recirculation - Use thegarden hose to recirculatethe chlorinated water backinto the top of the well andwash down the inside ofthe casing for at least30 minutes (the longer the

better) with the chlorinatedwater. Do not start therecirculation until waterfrom the hose is clear. Donot discharge turbid water from the hose back into the well. During this recirculation process,water circulates from the pump, through the drop pipe,service line, pressure tank, distribution piping, and hoseback into the top of the well. Recirculation enhances thechlorination process by exposing these surfaces tochlorinated water and cleaning water contact surfaceswithin the well.

Some water well drilling contractors have extended therecirculation time to several hours. Extended recirculationhas been shown to increase the effectiveness of thedisinfection process. During extended recirculation a sealneeds to be placed on the wellhead to keep contaminantsfrom entering the well.

Where practical, the pump intake should be located asclose to the bottom of the well as possible during thisperiod of recirculation. After completing the recirculation,install the permanent well cap.

Recirculation of chlorinated water

Protected wellhead during

recirculation


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7. Open taps -Open each tap within the home, one at a time, starting closest to the pressuretank, and run water until a strong chlorine smell is present. Check with a chlorine test strip,then close the tap. Do not forget to flush each hot water tap. See the Distribution SystemDisinfection section of this manual for a more detailed description of procedures to be used todisinfect a distribution system.

8. Contact time. Allow the chlorine to remain in the water supply for 4 to 12 hours, or overnight

(Lehr, et al., 1988). Contact time is an important part of the chlorine treatment process. Thelonger the chlorine remains in the water supply system, the better the chance that the chlorinewill contact and kill microorganisms that may be present. Water use during the contact timeshould be minimized to assure that residual chlorine remains in the well. The well drillingcontractor should notify building occupants that the water is being disinfected and warned notto consume or bathe in the water until the disinfection is complete.

9. Flush. After the contact period, pump to waste to remove the chlorine. Flushing should be

continued for at least one hour after a chlorine smell can no longer be detected. This helpsassure that all traces of chlorine have been removed from the system. Flushing the well for anextended period of time after treatment with chlorine will also help clean the system becauseof the scouring action of the water.

While pumping to waste, use a hose to discharge into the yard, roadside ditch, or to anotherpoint where a nuisance will not be created. Avoid pumping strong chlorine solutions ontolawns or landscape plants. Do not run the water into the household plumbing, and subsequently into the septic

tank/tile field, during this pumping period. This may overload the drainfield. Do not run the water into a lake, stream or other body of water.

10. Reactivate treatment systems. When all traces of chlorine are gone, place the already

disinfected water treatment units back "on-line.

11. Sample. Before collecting a water sample for bacteriological analysis, check for residualchlorine using a chlorine (swimming pool) test kit or a chlorine meter. If chlorine is still present,continue to flush. If a test kit or meter is not available, continue to flush for at least 2 hours

after there is no chlorine smell, before collecting the bacteriological water sample. (See theWater Sampling for Coliform Bacteria section of this manual for further details).

Turbidity as a result of the chlorination process

Water in a water supply system that has been treated with chlorine can be turbid due to the effect ofthe chlorine on contaminants in the water (such as iron and biofouling). Extended continuouspumping normally clears the water of turbidity, unless the turbidity is the result of a well constructiondefect.


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DISTRIBUTION SYSTEM DISINFECTION

GeneralFor purposes of this document, the distribution system includes the pressure tank, the water heater,water treatment equipment, piping system, and fixtures.

There are two important steps in the disinfection process for existing distribution systems:

1. Flushing

2. Treatment with chlorine

Both are essential to assure that contaminants that have been introduced into the distributionsystem are effectively removed.

FlushingFlushing of the distribution system helps remove loose materials that may be in the system. Thesematerials can interfere with the chlorination process by using up available chlorine and preventingthe chlorine from coming in contact with the bacteria that may be lodged in the materials. Thematerials may include:

1. Debris that has accumulated in the pipes, including loose bits of solder, metal shavings, dirt, or

loose scale.2. Greases.3. Flux residuals from the soldering of copper pipes.4. Solvents and glues from the solvent welds used with plastic pipes.5. Insects that may have entered the distribution system during construction.6. Sand or other material from the well that may have been pumped into the distribution system.

As with the water well application, water moving through the distribution system can effectively helpremove bacteria by the scouring and diluting action of the water.

The distribution system flushing process should not take place until the water from the well is free ofsand, silt, or other turbidity. If a problem of this nature exists, it must be corrected before flushing of

the distribution system.

Flushing must take place before chlorine treatment of the well or distribution system.

The flushing of the distribution system should take place in the following order:

1. Pressure tank. If the pressure tank has debris in it, it may be discharging debris into thedistribution system. It would be counter productive to flush the pipes first, only to have debrisreintroduced into them from the tank.

2. Hot water tank.3. Water treatment systems.4. Distribution system piping and fixtures.

Pressure Tank FlushingConventional galvanized tanks: These tanks normally have an inlet and outlet above the

bottom of the tank. This design leaves a basin at the bottom where scale and other sedimentaccumulate.

The older style tanks found in residential installations have no access openings into the tankwhich would allow for cleaning of the tank, so the only way to attempt cleaning of these is byflushing, which is, at best, marginal. The tank can be filled and drained repeatedly until


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discharge water is no longer turbid, but this will in no way assure removal of contaminants thatmay be in the debris that remains in the bottom of the tank.

Removal of an old galvanized tank and replacing it with a bladder/diaphragm type tank is themost practical, efficient way of attempting to correct a coliform bacteria problem that may berelated to the tank.

Bladder/diaphragm tanks: These tanks normally have only one pipe entering the tank. This

opening serves as both the inlet and outlet for the tank and is located at the bottom center of thetank. These tanks are flushed out during each pump cycle, since the tank is nearly emptied of all

water when the pump comes on. Most of the sediment or scale that may have entered the tankwith the water is flushed out as the water is discharged from the tank.

Water Heater Flushing and Treatment with Chlorine

Hot water tanks have a basin at the bottom of the water heater tank that allows for the collection ofscale and other debris that may have been introduced into the tank from the well or mineral in thewater. Biofilms may also be present in the tanks. These biofilms and debris must be removed toeffectively disinfect a water heater tank. However, thorough cleaning of most domestic water heatersis not possible, since there are no access openings into the tank. The only way to attempt cleaningis by flushing, using the boiler drain (faucet) near the bottom of the tank. Flushing may removemuch of the debris in the tank, but complete removal of all material cannot be assured. The flushingof the water heater must take place prior to the addition of chlorine into the water supply system.

Suggested water heater flushing procedures:

1. If electric, turn off power to the water heater element or if gas, set the control to the lowesttemperature or off position.

2. Turn off the valve on the water inlet pipe delivering water to the hot water tank.3. Open the faucet at the base of the water heater, and allow water on the water heater tank to

drain. It may be necessary to open a hot water tap at one of the distribution system fixtures torelieve the vacuum that is created as water drains from the tank.

4. After the tank is empty, close the faucet.5. Open the water inlet pipe valve to refill the tank.6. Repeat steps 2 through 5 until the water being discharged from the boiler drain is free of any

debris or turbidity.7. Open the water inlet pipe valve, and turn the water heater control back to the operating

position.

After the water heater tank has been cleaned to the extent possible by following the above flushingprocess, treat the tank with chlorinated water. This chlorinated water normally comes from the well,where the chlorine has been introduced into the system.

As a supplement to treatment with chlorine, the hot water tank, as well as the hot water pipingsystem, may be disinfected by turning the heat control on the hot water heater to High. This willnormally generate hot water temperatures at or above 140

oF, temperatures which will kill most

bacteria. This hot water can be circulated through the hot water distribution piping to enhance the

disinfection of that portion of the water supply. Extreme caution must be used to avoid scaldinginjuries by restricting use of the water supply when the hot water temperature has been increased.

Water Treatment Equipment Flushing and Chlorine Treatment

Household water treatment systems commonly encountered in a home include water softeners,reverse osmosis systems, iron removal systems, hydrogen sulfide treatment systems, and cartridgefilters. Organic and inorganic (calcium, magnesium, iron, etc) nutrients which are present in manywater supplies will concentrate in these treatment systems. The presence of these nutrients along


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with the large surface area provided in resin beds and on filter cartridges (Geldreich, et al., 1985)facilitate bacterial growth, and are often the source of bacterial contamination of water supplies(Keller, 1991).

Following are some general water treatment unit cleaning and disinfection procedures to consider:

1. Follow water treatment systems manufacturers recommended cleaning and disinfectionprocedures.

2. Water softener resin bed disinfection procedures (Keller, 1991), in the absence of the unitmanufactures recommendations for disinfection:a. Fully regenerate the resin bed to the sodium form before starting the disinfection

process. This will help prevent metals from precipitating in the bed, causing fouling.Most units have a control setting for this manual regeneration.

b. Place 4 ounces of standard house hold bleach into the brine well of the salt tank forevery one cubic foot of resin in the treatment unit.

c. Again put the unit into the regeneration mode. This regeneration pulls the bleach fromstep b above into the resin bed.

d. It is advantageous to interrupt this second regeneration process and let the bleach sit inthe tank for an hour. This will allow greater contact time for more complete disinfection.Make sure there is a residual chlorine level in the effluent before shutting down the

regeneration.e. After the completion of the second regeneration, to put the unit through a third

regeneration. This will help remove any debris that may have broken loose during thedisinfection process.

3. The brine (salt) tank associated with a water softener should be periodically cleaned. Watersoftener salt may contain sand and other impurities that accumulate as sludge in the bottom ofthe tank as the salt dissolves. The sludge that builds up should be removed periodically toprevent this from becoming a place to harbor bacteria that may then contaminate thedistribution system piping when the water softener regenerates.

4. Canister type cartridge filters should be periodically cleaned by putting the filter unit in the

bypass position, and removing the canister housing and filter. Clean and rinse the canisterhousing with chlorinated water, and install a new cartridge filter (properly dispose of the oldone). Do not rinse the new cartridge filter with chlorinated water.

Piping and Fixture Flushing1. Put water treatment equipment (such as water softeners or filters) in the bypass position.2. Remove and clean faucet aerators or similar devices on the outlets.3. Each outlet (hot and cold) in the distribution system needs to be individually flushed, one at a

time. Outlets include, but are not limited to, sinks, outside taps, bathtubs, shower heads,toilets, laundry sinks, dishwashers, refrigerator ice makers, and clothes washing machines.

4. Start with the outlet closest to the source of water (pressure tank).5. Turn on the outlet to full volume and flush it until the water being discharged is free of any

debris or turbidity.6. If the outlet is a mixing type fixture (hot and cold water using the same outlet), flush each side

separately.7. Turn off that outlet and proceed to the next closest outlet. Repeat the flushing process.8. Continue this process, one outlet at a time, until all outlets have been initially flushed.9. By flushing the outlets one at a time, the flow volume and velocity are maximized to get the

most effective flushing possible.10. The longer the system is flushed the better.11. Reinstall the cleaned aerators or similar devices that were removed from the outlets prior to

the flushing procedure.


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Chlorine Treatment of the Distribution SystemThe objective of the treatment process is to assure that chlorinated water is flushed through everypart of the distribution system including all pipes, fixtures, outlets and water heaters.

After the entire distribution system has been flushed as described above, it is ready for treatmentwith chlorine. Once the chlorine has been introduced into the well and pressure tank the chlorinecan be run into the distribution system. See the Chlorinating a Water Supply Using SimpleChlorination section of this manual for well chlorination information.

This chlorinated water should be tested to assure that at least 50 ppm chlorine concentration ispresent. Test at several points in the distribution system.

Introduce the chlorinated water from the well into the distribution system, as follows:

1. Assure that all water treatment equipment is in the by-pass position.2. Starting with the outlet closest to the pressure tank, turn it on until the strong smell of chlorine

can be detected. Check with test strips. Outlets include, but are not limited to, sinks, outsidetaps, bathtubs, shower heads, toilets, laundry sinks, dishwashers, refrigerator ice makers andclothes washing machines.

3. Turn the outlet off and proceed to the next closest outlet.4. Continue this process until all fixtures and pipes have been filled with the chlorinated water.

5. Both hot and cold water piping and fixtures must be turned on (separately) until the chlorinesmell can be detected.

6. It may take an extended flushing period until the chlorine smell can be detected in the first hotwater outlet flushed. This is because it will take some time for the water heater to fill with thechlorinated water from the well.

7. After all outlets have been flushed and chlorinated water is in the entire distribution system, thechlorine should remain in the system at least overnight, and as long as possible.

8. The chlorine may be flushed from the system the next day. The chlorinated water should notbe discharged into a septic tank/tile field system. It is suggested that a hose be attached to anoutside tap, and the chlorinated water discharged to a road side ditch, a sprinkler head, intothe yard, etc. Do not discharge to a lake, stream, or other body of water.

9. Continue to run the water until all traces of chlorine are gone from the system. Use a chlorine

test kit to verify.10. Allow the water to run an additional 1 to 2 hours to assure that all traces of chlorine have been

removed from the system.11. Put water treatment equipment back on line. The water treatment equipment must have been

flushed and disinfected as described earlier.12. Collect and submit a water sample for coliform bacteria analysis.

Difficult Cases

If chlorination and flushing of a distribution system is not successful in removing coliformcontamination, consider flushing the system with a 10 percent vinegar solution (prepared from white,distilled vinegar) in order to remove any biofilm accumulated. There are also biodispersants on themarket that are very effective at biofilm removal. In most cases, however, pH controlled chlorination

is more effective than biodispersants in disinfecting distribution systems, especially where highheterotrophic plate counts are found.

Simple Chlorination

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